An organic electroluminescence (referred to herein as organic EL) display device is arranged with a light emitting element in each pixel and displays an image by individually controlling emitted light. A light emitting element has a structure in which a layer including an organic EL material (referred to herein as [organic layer]) is sandwiched between a pair of electrodes distinguished as an anode and a cathode. When electrons are injected from the cathode to the organic layer and holes are injected from the anode to the organic layer, the electrons and holes recombine, thereby the discharged excess energy excites light emitting molecules within the organic layer which then emit light by de-excitation.
The anode within each light emitting element in an organic EL display device is arranged as a pixel electrode for each pixel and the cathode is arranged as a common electrode applied with a common voltage across a plurality of pixels. The organic EL display device controls emitted light of a pixel by applying the voltage of a pixel electrode to each pixel with respect to the voltage of this common electrode.
Here, although it is sufficient that a larger voltage is applied in order to obtain a better luminance, this results in shortening the life of a light emitting element. On the other hand, only about 20% of the light emitted by an organic layer is utilized. The remaining 80% is wave-guided through layers or within a substrate while repeatedly being totally reflected due to differences in interlayer refractive indexes, is attenuated and absorbed within a layer. As a result, various efforts are being made in order to obtain a high light extraction efficiency.
For example, an organic EL display device is disclosed in Japanese Laid Open Patent Publication 2004-335276 in which concave convex parts are formed in the surface of an insulation film formed on a lower layer of a pixel electrode. In an organic EL display device configured in this way, light which is output from an organic layer is emitted after passing through a pixel electrode and insulation film. At this time, the concave convex parts formed between the pixel electrode and insulation film prevent emitted light from being reflected by an interface surface thereof. However, the organic EL display device disclosed in Japanese Laid Open Patent Publication No. 2004-335276 only considers the extraction efficiency of light in a front surface direction in an organic layer flat part.